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March 17, 1964 w. N. STEWART in 3,125,171

OFFSHORE DRILLING EQUIPMENT Filed Oct. 27, 1958 4 Sheets-Sheet 1VV////am A o/on Jfewarzjfl INVENTOR.

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INVENTOR.

ATTORNEY March 17, 1964 w. N. STEWART m OFFSHORE DRILLING EQUIPMENT 4Sheets-Sheet 3 Filed 001'.- 27, 1958 W////c7/77 /V0/a/2 Jfe war/,2?

INVENT OR.

ATTORNEY March 17, 1964 w. N. STEWART m OFFSHORE DRILLING EQUIPMENTFiled Oct. 27, 1958 u a /l- 4 Sheets-Sheet 4 INVENTOR.

QMZZWU/K United States Patent 3,125,171 ()FFSHORE DRILLING EQUWMENTWilliam Nolan Stewart 111, Houston, Tex., assiguor to Zapata (DE-ShoreCompany, Houston, Tex., a corporation of Delaware Filed Get. 2.7, 1958,Ser. No. 769,791 2 Claims. (Cl. 175-5) This invention relates to thedrilling and servicing of submerged wells and consists particularly innovel apparatus and method for stably mounting and supporting the wellcasing, including wellhead instrumentalities, upon the water bottom anddrilling the well by the use of power means carried on a free floatingvessel brought to the immediate vicinity of the well casing.

Heretofore, offshore or submerged wells, particularly oil wells, havebeen drilled either from elaborate, massive, permanent or semi-permanentinstallations, actually artificial islands, built upon the water bottomand extending to a platform above the surface of the water, or from freefloating vessels which have been connected to the wells by complicated,flexible elements which are diflicult to disassociate from the well orthe vessel in case it is necessary for the vessel to leave the scene, asin case of an impending storm. The permanent platform method is veryexpensive and often may not be justified in view of the uncertainties inoil well exploration. Furthermore, such permanent structures must bevery strongly built so as to withstand the bulfeting forces of wind andwater as well as colliding vessels. Attempts to drill submerged wellsfrom freely floating vessels, also, have necessitated very substantialexpenditures in special equipment in an eifort to accommodate thedrilling equipment to motion due to waves, wind, and tide whilepermitting ready location of the well in case it is necessary for thevessel to leave the vicinity.

In some recent instances, submerged wells have been drilled with the useof submerged wellhead and drill powering equipment which have obviousdisadvantages. On the other hand, it has not been practical heretoforeto mount a conventional drill powering means on a free floating vesseland connect the power means to the well by a simple drill string, as isused in ordinary land drilling.

Accordingly, the main object of the present invention is to providenovel means and method for drilling a submerged well, particularly anoil or gas well, with the use of powering equipment carried wholly onand by a free floating vessel and without the need of special flexibledrill strings and casings.

Another object is to provide novel means for supporting and protectingan oil well drilled into a submerged formation.

Another object is to provide a novel well support frame which, while ofrelatively light and inexpensive construction, is capable of supportingand protecting the usual well head instrumentalities.

. Another object is to provide guard and support structure for asubmerged well, including a platform above the surface of the water formounting workover instrumentalities.

Still another object is to provide vessel mounted power equipment and asubmerged well casing construction which are adapted to manipulate andreceive a powered drill string with suflicient lateral play toaccommodate the relative motion of the vessel, without unduly strainingany of the parts.

Briefly, the present invention consists in a power swivel which ismounted for vertical and limited swivelling motions on an uprighttrolley rigidly carried by the vessel. The usual draw works are providedfor controlling the vertical motion of the swivel and the drill stringconnected thereto. The string extends over the side of the vessel 'ofvertical leg 25 as a protective bumper.

and into a hollow leg of the novel well support and guard frame, whichleg serves as the upper portion of the well casing. Alongitudinally-extensible coupling is provided in the drill string andswivelling is provided between the power swivel and the mounting trolleyso that, together with a certain amount of lateral play provided betweenthe drill string and casing, the rocking and swaying of the vessel dueto wind, wave, and tidal action is accommodated without undue strainingof the drill string or casing.

In the accompanying drawings which illustrate the invention, FIG. 1 is aside view of the novel well support and guard structure and a drillingbarge anchored alongside the same.

FIG. 2 is a top view of the well guard and support structure.

FIGS. 3 and 4 are side views of the well guard and support structure.(Taken at to each other.)

FIG. 5 is a somewhat schematic representation of the top portion of thewell guard and support structure, showing the casing and wellheadequipment and also indicating the position of the barge during thedrilling operation, parts being broken away and sectioned.

FIG. 6 is a schematic front view showing the upper parts of the wellguard and support structure and the vertical trolley with travellingblock and power swivel mounted thereon and connected to a drill stringwith an expansible joint, parts being sectioned.

FIG. 7 is a side view of the parts in FIG. 6, but showing the travellingtrolley and its appendages inclined, as during rolling of the barge,parts being sectioned.

FIG. 8 is a detail horizontal section taken substantially on line 8-8 ofFIG. 7.

' FIG. 9 is a side view of the upper portion of the well guard andsupport structure showing workover apparatus mounted thereon.

The novel drilling apparatus consists broadly in a free floating vesselor barge 1d having suitable anchors attached by means of chains 11 forstabilizing the barge at the drilling site. Mounted on the barge are acrane, generally indicated at 12, and other necessary drilling equipment13, including the usual draw works and pumps, storage equipment andhandling machinery for casing and tubing, and storage facilities fordrilling fluid, as well as living quarters for the crew. Projectingsidewardly from the deck of the barge is a cantilever platform 14 uponwhich is mounted a derrick 15 having the usual pipe mounting racks 16and crown block (not shown) at the top. Rigidly mounted at the center ofthe derrick is a fabricated I-beam guide or trolley 17 which mounts forlongitudinal movements therealong (FIGS. 6-8) the travelling block 18and a power swivel hydraulic motor mechanism 19. The power swivel,represented externally, is a commercially-obtainable hydraulic unit.

Stably mounted on the bottom of the body of water beneath cantileverplatform 14 is a rigid, welded well guard and support structure 20 ofgeneral tripod form, including hollow legs 25, 26 and 27, leg 25 beingvertical and legs 26 and 27 being tilted with respect to leg 25 and toeach other, as shown in FIGS. 3 and 4. The three legs are mutuallysecured together and braced by transverse strut members 28. At thebottom of the tripod structure, is a mud pad 29 consisting of ahorizontal platform secured to the tripod legs near the bottomextremities thereof.

At the top of the tripod structure, is a combination bumper and platformmounting frame, including relatively short, vertical posts 30 and 31extending, respectively, along the upper parts of legs 26 and 27 andsecured thereto by short cross pieces 32 and 33, and welded at theirlower ends to the legs. A network of vertical legs 34 and horizontalbrace pieces 35 extends around the outer side Horizontal pieces 35 aresecured directly to pipe 25 by radial struts 36. Topmost horizontalpiece 35 is continued to legs 26 and 27, as at 37 and 37a and a piece 33completes the uppermost bumper framing. intermediate and lowerhorizontal bumper pieces 35 are extended to legs 26 and 27 by pieces 35and 49. Directly connecting vertical leg 25 and tilted legs 26 and 27 atthe top are diverging horizontal pieces 41 aligned horizontally withpreviouslymentioned element 35 of the bumper. A platform 42 is providedon uppermost horizontal braces 38 and 41 and guard rail structure 43,4-4 projects above the bumper framing, its legs 43 being respectivelyaligned with previously-mentioned vertical bumper elements 3t and thecenter one of elements 34. Guard rail 44 extends entirely around theupper part of the tripod and has curved corners of rather large radii.

The tripod structure just described constitutes a guiding jacket fortubular piles 45, 46 and 4-7, snugly received in legs 25, 25 and 27 anddriven securely into the formation 43 at the bottom of the water. Thejacket structure is designed to extend from the water bottom slightlyabove the maximum water level for maintaining the conventional wellheadinstrumentalities, generally designated at 49 (FIG. above the Water. Allof the upper parts of legs 25, 26 and 27, the upper bracing members 28and the bumper elements are jacketed, as indicated at 5G, by a suitablenon-corrodible material, such as Monel metal. Pile 45 extending throughvertical leg 25 constitutes the upper element of the well casingstructure, as will be mentioned hereafter. An inner casing member isshown at 51. A drill fluid return line is provided at 52.

As best shown in FTGS. 6 and 7, travelling block 18 has lateral arms 53,having rollers 54, running in the side channel of I-beam 17. As shown indetailed FIG. 8, the rollers loosely fit the I-beam channels, beingmerely generally guided thereby. The power swivel, having hydraulicpressure and exhaust lines 55, and drilling fluid line 56 attachedthereto, also has lateral arms 57 mounting rollers 58, similar torollers 54, running along the I- beam channels. Play is provided betweenrollers 53 and the I-beam channels to permit a certain amount of tiltingof the power swivel with respect to the trolley. Arms 57 have pivotingconnections 59 with the power swivel casing which is supported fromblock 18 by means of a hook 60 and pivoted loop 61.

The power swivel has a depending drive shaft 62 which is threadedlysecured to the end of drill string 63. FIG. 7 shows the power swivelmuch closer to the wellhead than would be the case in practice. Thetilting of the power swivel and resultant flexing of the drill string toaccommodate the tilting of the trolley is correspondingly exaggerated,for clearer illustration. Mounted in the drill string within the well isa longitudinally extensible coupling or slip joint 64, such as a bumpersub (FIG. 5), which accommodates relative vertical motions of the drillbarge and well.

In the operation of my novel offshore drilling apparatus, the well guardand support apparatus is first transported to the site and placed uponthe water bottom, as with the use of crane 12, shown in FIG. 1. It isfeasible to use this type of well guard and support structure in waterup to 150' deep, when the structure is of steel and in even deeper waterwhen the structure is formed of light metal such as aluminum, thelimitations being in the ability of the crane to handle the jacketstructure. After the tripod structure is mounted on the water bottom,with mud pad 25 resting on the mud, hollow pipe piles are driven throughthe jacket legs into the submerged structure for firmly anchoring thewell guard device. Vertical leg 25 is, of course, positioned directlyover the point of drilling and pile 45 extending therethrough serves asthe upper well casing member. As the drilling proceeds, an inner,reduced casing member 51 is run and appropriately cemented in the wellknown manner.

FIG. 7 shows trolley member 17 tilted to illustrate how the noveldrilling apparatus accommodates rocking of the barge and the resultantrelative motion between derrick 16 and trolley 17 and the stationarywell casings and wellhead structure. Wellhead instrumentalities 49, suchas a blowout preventer and master valve, are of such types as to permita certain amount of lateral play of drill string 63 therein. This play,together with permissible flexing of the drill string itself, issufficient to accommodate rocking of the barge without undue strainingof the drill string. Such rocking motion, longitudinally as well aslaterally, is further facilitated by the non-rigid mounting of powerswivel 19 relative to trolley 17 and travelling block 13. The opening 7it in platform 14 is adequate to accommodate all lateral play of thedrill stem incident to rocking of the barge. Relative vertical motionbetween the casings and wellhead and the barge are accommodated byslipjoint 64 provided in the drill string at a suitable point within thecasing. Such a slipjoint positioned at a fixed point above the bit,insures the maintenance of a substantially uniform load on the bit,irrespective of vertical movements of the barge and drilling equipmentmounted thereon.

FIG. 9 shows the novel well guard and support struc ture utilized as aworkover platform, thus dispensing with the necessity of maintaining aspecial drill barge at the location. A somewhat extended platform isprovided at 65 and mounted thereon is a portable tower 66 and an engine67 and winch 68. Wellhead instrumentalities are shown at 69.

Accordingly, there is provided means for drilling a submerged well,utilizing, substantially simpler apparatus than has heretofore beenprovided for the purpose, while permitting the mounting of all of thedrilling apparatus on the barge itself for transport from place toplace. The casing support and guard structure is substantially simplerthan is required where such structure must support the complete drillingequipment. Yet, the structure is adequate for protecting the casingagainst wave and wind action as well as impact from floating objectssuch as barges. In a practical embodiment, vertical leg 25 of the jacketframe is made of 33 inch O.D. pipe, while tilted legs 26 and 27 are madeof 24 inch O.D. pipe. The vertical pile is 30 inch O.D. pipe while thetilted piles are 20 inch O.D. pipe. Braces 28 are made of 10%" OD. pipe,as are horizontal bumper pieces 36, 38, 39, and 4t) and vertical pieces30. All of the legs and brace structures are firmly welded together in arigid structure. I have found that this type of well guard and supportstructure will withstand an impact of a freely-floating 300 ton bargetravelling at 2 knots.

The full guard rail 44 is of particular importance in permitting thedrilling barge to be positioned about the well as desired, for instance,with its nose into the wind to reduce the pull on the anchors. In casethe wind should shift, or, if for other reason it is desirable to do so,the vessel can be swung around the tripod without departure from theprotecting bumper rail.

The flexing and vertical and lateral play provided for the drill stringand its powering means are adequate for the purpose, so that thegimbal-mounted rotary, as previously mounted on the drill barge, and thecomplications incident to the mounting of the drilling equipment in orabove the water upon a permanent or semi-permanent in stallation areavoided. The invention may be modified in various respects as will occurto those skilled in the art and the exclusive use of all modificationsas come within the scope of the appended claims is contemplated.

I claim:

1. Olf shore drilling apparatus comprising a hollow casing projectingfrom the water bottom to the vicinity of the surface of the water, ahollow pile received within said casing and firmly embedded in the waterbottom, a floating vessel anchored alongside and independently of saidcasing, a platform projecting beyond the edge of said vessel and subjectto rocking action relative thereto, drill powering means mounted on saidplatform above said casing and pile, well head instrumentalities mountedon the upper portions of said casing and pile, and a torquetransmitting, longitudinally flexible drill string extending from saidpowering means through said platform and said instrumentalities and saidhollow pile, said casing and instrumentalities terminating substantiallybelow said platform and said powering means to expose a substantiallength of said string for flexing during rocking of said vessel, therebeing substantial clearance between said string and saidinstrumentalities and upper portions of said casing and pile permittinglateral play of said string to accommodate flexing thereof.

2. Apparatus for use in performing work in a well in a submergedformation comprising a hollow pipe extending from the water bottom tothe vicinity of the surface of the water, a hollow pile received in saidpipe and firmly driven into the water bottom to form a well casing, afloating vessel anchored alongside said pipe but structurallydisconnected therefrom, a platform projecting from said vessel over saidcasing, drill powering equipment carried by said platform andconstrained for rocking action therewith about the center of gravity ofthe vessel and a drill string extending from said powering equipmentinto said casing for operating a well tool, there being a substantialunrestrained length of said string between said powering equipment andsaid casing to accommodate the flexing of said string due to rocking ofsaid vessel.

References Cited in the file of this patent UNITED STATES PATENTS Re.24,083 McNeill Nov. 1, 1955 89,794 Rowland May 4, 1869 285,628 Jones etal Sept. 25, 1883 496,729 Fairchild May 2, 1893 525,795 Palmer Sept. 11,1894 1,175,725 Dunbar Mar. 14, 1916 1,829,304 Schroeder Oct. 27, 19312,001,576 Johnson May 14, 1935 2,026,879 Ferguson Jan. 7, 1936 2,515,540Willey et a1 July 18, 1950 2,637,978 Evans et a1 May 12, 1953 2,699,321Nelson Jan. 11, 1955 2,854,215 Cox et a1 Sept. 30, 1958 2,906,500 Knappet a1 Sept. 29, 1959 3,004,612 Kofahl Oct. 17, 1961 UNITED STATES PATENTOFFICE CERTHHCATE OF CORRECTHIN Patent N0. 3,l25,l7l March 17, 1964William Nolan Stewart III It is hereby certified that error appears inthe above numbered patent requiring correction and that the said LettersPatent should read as corrected below.

Column 3, line 9, for "element" read elements line 34, for "channel"read channels e-;-column 4, line 75, before the comma insert and subjectto rocking action relative thereto column 5 line 1 strike out "andsubject to rocking action relative thereto Signed and sealed this 14thday of July 1964 @EAL) Attest:

ESTON G. JOHNSON EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. OFF SHORE DRILLING APPARATUS COMPRISING A HOLLOW CASING PROJECTINGFROM THE WATER BOTTOM TO THE VICINITY OF THE SURFACE OF THE WATER, AHOLLOW PILE RECEIVED WITHIN SAID CASING AND FIRMLY EMBEDDED IN THE WATERBOTTOM, A FLOATING VESSEL ANCHORED ALONGSIDE AND INDEPENDENTLY OF SAIDCASING, A PLATFORM PROJECTING BEYOND THE EDGE OF SAID VESSEL AND SUBJECTTO ROCKING ACTION RELATIVE THERETO, DRILL POWERING MEANS MOUNTED ON SAIDPLATFORM ABOVE SAID CASING AND PILE, WELL HEAD INSTRUMENTALITIES MOUNTEDON THE UPPER PORTIONS OF SAID CASING AND PILE, AND A TORQUETRANSMITTING, LONGITUDINALLY FLEXIBLE DRILL STRING EXTENDING FROM SAIDPOWERING MEANS THROUGH SAID PLATFORM AND SAID INSTRUMENTALITIES AND SAIDHOLLOW PILE, SAID CASING AND INSTRUMENTALITIES TERMINATING SUBSTANTIALLYBELOW SAID PLATFORM AND SAID POWERING MEANS TO EXPOSE A SUBSTANTIALLENGTH OF SAID STRING FOR FLEXING DURING ROCKING OF SAID VESSEL, THEREBEING SUBSTANTIAL CLEARANCE BETWEEN SAID STRING AND SAIDINSTRUMENTALITIES AND UPPER PORTIONS OF SAID CASING AND PILE PERMITTINGLATERAL PLAY OF SAID STRING TO ACCOMMODATE FLEXING THEREOF.